VIRTUAL STEERING OF INDUCTION TOOL ATTENUATION AND PHASE DIFFERENCE MEASUREMENTS

摘要

An apparatus and method that provide steerable measurements of attenuation a nd phase difference are disclosed. In a preferred embodiment, a logging tool is provided with two triads of orthogonal receivers and a triad of orthogonal transmitters. A controller in the logging tool fires selected transmitters singly and in pairs, and determines measurements of ratios between signals received by the receiver triads. The measurement of sixteen ratios i s sufficient to allow determination of attenuation and phase difference that would be measured by virtually steered receivers according to equations provided herein.